Structure for reducing the drag of a ship and its application

ABSTRACT

A structure for reducing the drag of a ship and its application thereof is provided. The structure for reducing the drag of a ship comprising at least one turbulence generator which is installed on the side surface between the widest section and the aft end or on the bottom surface between the deepest portion and the aft end of the ship. The arrangement of the turbulence generator can generate turbulence to reduce the drag of the ship, and thereby increase the speed of the ship or reduce fuel consumption as well.

1. FIELD OF THE INVENTION

The present invention relates to the structure of a ship and its application thereof for reducing drag of the ship while sailing, particularly to a ship having a turbulence generator on the surface of the hull for generating turbulence to reduce drag of the ship and its application thereof.

2. DESCRIPTION OF RELATED ART

Ship suffers the drag while sailing which slow down the speed of ship. The drag causes not only more fuel consumption, but also wear down the motor and the transmitting mechanism, as well as produces more exhaust gas and longer time to complete the voyage. The environmental pollution, extra fuel consumption and time loss to the transportation field are inevitable.

Although the streamlining of the shape of ship's hull is helpful to reduce drag, but the effect is still limited. Referring to FIGS. 1A and 1B, a perspective view of a conventional ship sailing in the water is shown. The ship 1 comprises a hull 100. The direction of sailing or heading of the ship 1 is depicted as H. The hull 100 comprises a fore end 11, an aft end 14, a widest section 12 and a deepest portion 13 in between the fore end 11 and the aft end 14. When the ship 1 sails, a relative velocity between the water and the hull 100 occurs. A boundary layer 31 is formed on the surface of the hull 100 while the ship 1 is sailing in the water. The boundary layer 31 appears on both sides and the bottom of the hull 100. The boundary layer 31 moves along simultaneously with the hull 100. The boundary layer 31 grows gradually from the fore to the aft of the ship 1 while sailing, thereby the increased cross-section area and accumulated volume weight of drag slows down the speed of the ship 1.

Furthermore, the maximum relative velocity between the hull 100 and the water occurs at the widest section 12, and the minimum relative velocity occurs at the fore end 11 and the separation point 15. The separating point 15 locates between the widest section 12 and the aft end 14 at both sides of the ship 1. Wake 34 appears behind the separation point 15. According to the Bernoulli's principle, the pressure is inversely proportional to the velocity of water flow, therefore the fore end 11 of the ship 1 suffers the maximum pressure, the pressure decreases gradually to the lowest level at the widest section 12, and then increases gradually to the maximum at the separation point 15. Therefore, the longitudinal total pressure between the fore end 11 and the widest section 12 is greater than the longitudinal total pressure between the widest section 12 and the aft end 14. The difference of the longitudinal pressure also causes the drag to the ship. Accordingly, aforesaid various kinds of drag are detrimental to the ship's speed.

In order to overcome the drag issue for a ship while sailing, the present invention provides a structure installed on the hull of a ship and the application thereof for reducing the drag of a ship, which comprises a turbulence generator with a special design to reduce thickness of the boundary layer to delay the separation and alter the separation point 15 further backwards in order to increase the pressure of the aft part of the hull 100, thereby reduce the drag when the ship sailing, and accordingly increase the speed of the ship as well as reduce the fuel consumption.

SUMMARY OF THE INVENTION

In view of achieving the aforementioned purpose, the present invention provides a structure installed on the hull of a ship and its application for reducing the drag of a ship, which comprises at least one or a plurality of turbulence generators installed on the surface of the hull of the ship to generate a beneficial turbulence and thereby reduce the thickness of the boundary layer on the surface of the hull and thereby delay the separation to increase the pressure of the aft part of the hull to speed up the ship.

The structure for reducing drag of the ship of the present invention comprises at least one turbulence generator. The turbulence generators are installed respectively on both side surfaces of the hull between the widest section and the aft end of the ship.

In another embodiment of the present invention, one or a plurality of turbulence generators are installed on the bottom surface of the hull between the deepest portion and the aft end of the ship.

In a preferred embodiment, the structure for reducing the drag of a ship of the present invention comprises a plurality of turbulence generators, among which two adjacent turbulence generators are arranged in array with a gap between every two adjacent turbulence generators.

In the preferred embodiment of the present invention, the structure for reducing the drag of a ship of the present invention comprises a plurality of turbulence generators, which are arranged in series as a stripe configuration without a gap to fit the particular shape of a ship.

In the preferred embodiment of the present invention, the turbulence generator comprises an impact surface facing the incoming flow for colliding with to generate turbulence.

In the preferred embodiment of the present invention, as the ship sails in water, the turbulence generator of the ship has a corresponding velocity with the water, the impact surface of the turbulence generator is of 60 degrees or less intersection angle with the keel line of the ship.

In another embodiment of the present invention, the impact surface of the turbulence generator is parallel or inclined at zero degree relative to the keel line of the ship.

In the preferred embodiment of the present invention, the configuration of the turbulence generator is a rectangle, a slanted-face rectangle, a polygon, a trapezium, a triangular pyramid, a cone, a semi-circular cone, a semi cone or any other various configurations.

In the preferred embodiment of the present invention, the turbulence generator is adhered, embedded, welded to the surface of the hull or is integrally installed with the hull.

In the preferred embodiment of the present invention, the turbulence generator may be made of metal, plastic, wood, bamboo, glass, clay, ceramic or composite materials.

The structure for reducing the drag of a ship and its application according to the present invention comprises a hull and at least one turbulence generator. The turbulence generator is installed on the side surface between the widest section and aft end of the hull, or on the bottom surface between the deepest portion and the aft end of the ship to generate turbulence, thereby reduce the drag of the ship.

By installing at least one turbulence generator on the surface between the widest section and the aft end or the deepest portion and the aft end of the hull in the present invention may generate a beneficial turbulence behind the turbulence generator to thin the boundary layer, which in turn may delay the separation to reduce the drag of the ship and effectively increase the speed of the ship. Consequently, both fuel consumption and navigation time can be effectively saved.

BRIEF DESCRIPTION OF THE DRAWING

For a more complete understanding of the present invention, reference will now be made to the following detailed description of preferred embodiments taken in conjunction with the following accompanying drawings.

FIGS. 1A and 1B show the water flow diagram of a conventional ship sailing in the water.

FIGS. 2 and 2A illustrates the structure of the turbulence generator according to an embodiment of the present invention.

FIG. 3 illustrates the stress acting on the turbulence generator by the current according to an embodiment of the present invention.

FIG. 4 illustrates a boundary layer in the laminar flow.

FIG. 5 illustrates a boundary layer in the turbulent flow.

FIG. 6 illustrates the stream lines on the underwater surface of a ship when the water flows through the ship.

FIG. 7 illustrates the stream lines behind the turbulence generator installed on the underwater surface of the aft part of the hull.

FIG. 7A illustrates an enlarged view of the portion B of FIG. 7.

FIG. 8 illustrates the turbulence generator itself which is parallel to L and H, produces minimum drag to navigation.

FIG. 9 illustrates a plurality of turbulence generators disposed on a port side or bottom hull surface of the ship.

FIG. 10 illustrates the same turbulence generators disposed on the hull of a ship according to the present invention viewed from the port side bottom.

FIG. 11 illustrates the turbulence generators disposed on the surface of the bottom of the hull and the turbulence generated by the turbulence generators.

FIG. 12 illustrates the turbulence generator of the present invention in various configurations.

FIG. 13 illustrates the boundary layer according to the present invention.

FIG. 14 illustrates a schematic diagram of the laminar boundary layer being fluctuated by the turbulence generator becoming the turbulent boundary layer according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION Embodiments

In order to lay out the above and other purposes, features and advantages of the present invention more explicitly, the embodiments described herein are incorporated by the accompanying drawings for the detailed description.

Referring to FIGS. 2 and 3, the variation and the effects of the current when it encounters the turbulence generator of the present invention is described as follows. As shown in FIG. 2 and FIG. 7, a turbulence generator 2 installed on the hull 100 of a ship 1 comprises an impact surface 21 facing the incoming flow of water for colliding with and generating turbulence when the flow collides with the impact surface 21. Current C has a relative velocity with the turbulence generator 2 when the ship 1 sails in the water. As shown in FIG. 2, when the current C flows pass through the turbulence generator 2 with an attack angle A, more turbulence V will be induced behind the turbulence generator 2 when the current C collides with the turbulence generator 2. While comparatively less turbulence V is induced with the turbulence generator 2 arranged parallel to the flow of the current C. Referring to FIG. 3, when the current C collides with the turbulence generator 2, the current C exerts a stress F on the impact surface 21 of the turbulence generator 2. The stress F includes a vertical component Fv perpendicular to the turbulence generator 2 and a horizontal component Fh parallel to the turbulence generator 2. The component Fv exerting on the turbulence generator 2 becomes a thrust force exerting on the turbulence generator 2. Due to the size of the turbulence generator 2 is substantially much smaller than the hull 100 of the ship 1, consequently the side thrust exerting on the turbulence generator 2 of the component Fv is relatively small. The component Fh is parallel to the turbulence generator 2, and thus no stress is exerting on the turbulence generator 2.

As described above, a turbulence V is generated behind the turbulence generator 2 by the current C when an angle of attack A is formed between the turbulence generator 2 and the stream line of the current C after colliding with the turbulence generator 2. Therefore, the turbulence generator 2 may be installed at the stern part of the ship 1 as shown in FIGS. 7 and 7A. In a preferred embodiment of the present invention, the turbulence generator 2 is installed on the underwater side surface of the hull 100 between the widest section 120 and the aft end 140 as shown in FIG. 9. Furthermore, as shown in FIG. 11 that not only a boundary layer 31 occurs on both sides of the ship 1 while sailing in the water, but also a boundary layer 31 occurs on the bottom surface of the hull 100 (referring to FIGS. 1A and 1B), so that a turbulence generator 2 may be also installed on the bottom surface of the ship 1 between the deepest portion 130 and the aft end 140 of the hull 100. In an aspect of the present invention, a plurality of turbulence generators maybe arranged adjacent to each other with or without a gap in between and deposed in a linear, such as a stripe or other configuration on the surface of hull 100 to fit some particular hull shape, as shown in FIGS. 9 and 10.

FIGS. 4, 5 and 14 respectively illustrate a boundary layer 32 of the laminar flow and a boundary layer 33 of the turbulent flow. The water flow velocity of the interface between the current C and the surface of the hull 100 is zero. The current C is slower near the surface of the hull 100. The length of the arrows in the figures represents velocity. Since the kinetic energy of the water molecule in the turbulent flow is higher, the water molecule with higher kinetic energy tends to relay the kinetic energy to the surface of the hull 100, such that the kinetic energy of the water molecule near the surface of the hull 100 increases, and accordingly increase the flow velocity of current C′. After the turbulence V is formed, the thickness of the turbulent boundary layer 33 is decreased compared with the thickness of the laminar boundary layer 32. Consequently, the drag caused by the current C to the ship 1 becomes correspondingly less.

FIG. 6 and FIG. 7 show a current C passes through the hull 100 of the ship 1. Since the fore end 110 and the aft end 140 of the hull 100 are pointed, the current C1 deflects downwards at the fore part of the hull 100. The current C2 deflects upwards at the aft part of the hull 100 after passing the widest section 120 of the hull 100. As shown in FIG. 7A, when the turbulence generator 2 is arranged horizontally, the current C deflects upward at the aft part which forms an angle of attack A with the impact surface 21 of the turbulence generator 2. As a result, the downstream from the turbulence generator 2 becomes the turbulence V, thereby the drag of the boundary layer 31 to the hull 100 is reduced. The keel line L is the central line between the fore end 110 and the aft end 140 of the hull 100 of the ship 1. The angle A between the impact surface 21 of the turbulence generator 2 and the keel line L may be less than 60 degrees. In a preferred embodiment of the present invention, the impact surface 21 of the turbulence generator 2 is parallel to the keel line L.

In addition, the turbulence V can increase the pressure to the aft part of the hull 100 and reduce the pressure difference between the fore and aft halves of the hull 100, thereby further reduce the drag caused by the pressure difference to the hull 100 of the ship 1 while sailing.

Referring to FIG. 8, which illustrates the influence of the turbulence generator 2 itself after installed on the surface of the hull 100 of the ship 1. Since the installed direction of the turbulence generator 2 is substantially parallel to the keel line L of the ship 1, the normal stress F′ of the current C acting on the normal direction of the turbulence generator 2 by the current C does not affect the speed of the ship 1. While the tangential stress F″ of the current C to the turbulence generator is parallel to the heading of the ship H, the resistance of the turbulence generator 2 comes from the tangential stress F″ is extremely low to the ship 1.

In an embodiment of the present invention, the hull 100 has a length of 6.246 m, width of 1.057 m, draft of 0.322 m, the turbulence generator 2 is a pyramid with a length of 2 to 10 cm, width of 0.5 to 2 cm, height of 0.5 to 1 cm. However, the configuration of the turbulence generator 2 applied in the present invention is not limited by the above example; the configuration of the turbulence generator 2 may be a rectangle, a slant-face rectangle, a polygon, a trapezoid, a pyramid, a triangular pyramid, a cone, a semi-circular cone or a semi cone as shown in FIG. 12. The dimensions of the turbulence generator 2 may be selected as desired in proportion to that of the hull 100.

In the preferred embodiment of the present invention, the turbulence generator 2 may be adhered, embedded or welded to the surface of the hull 100, or integrally installed with the hull 100. The material of the turbulence generator 2 can be made of metal, plastic, wood, bamboo, glass, ceramic or composite materials.

Referring to FIGS. 13 and 14, FIG. 13 is a schematic diagram of a boundary layer 31 when the current C flows through the hull surface of the ship 1. The velocity of the current C is slower while close to the hull surface and faster while apart from the hull 100. FIG. 14 is a schematic view of the laminar flow of the boundary layer 32 being fluctuated by the turbulence generator 2 becoming the turbulent boundary layer 33. As the turbulence generator 2 of the present invention installed on the hull 100, the turbulence occurs after the current C collides with turbulence generator 2, thereby the laminar boundary 32 becomes the thinner turbulent boundary layer 33.

In summary, the present invention can practically achieve the purpose of the invention by providing the turbulence generator on the underwater side surface between the widest section and the aft end of the ship, or on the bottom surface between the deepest portion and the aft end of the ship to generate turbulence, thereby to thin the boundary layer and delay the separation to increase the pressure to the stern part of the ship, therefore reduce the drag of the ship. Accordingly, the present invention can effectively speed up the ship as well as save the fuel consumption. It is industrial valuable and practically provides a novel improvement for a ship.

LEGEND

-   1 ship -   100 hull -   11, 110 fore end -   12, 120 widest section -   13, 130 deepest portion -   14, 140 aft end -   15 separation point -   2 turbulence generator -   21 impact surface -   31 boundary layer -   32 laminar boundary layer -   33 turbulent boundary layer -   34 wake -   A attack angle between the current and the turbulence generator -   C, C′, C1, C2 current -   F stress exerting on the turbulence generator -   Fv vertical component of the stress -   Fh horizontal component of the stress -   F′ normal stress to the turbulence generator -   F″ tangential stress to the turbulence generator -   H heading of the ship -   L keel line -   V turbulence 

What is claimed is:
 1. A structure for reducing the drag of a ship and its application, comprising: a hull, comprising a fore end and an aft end, wherein a keel line is formed between said fore end and said aft end of said hull; and at least one turbulence generator, provided on the side surface between the widest section and the aft end of said hull, or on the bottom surface between the deepest portion and the aft end of said hull, thereby the arrangement of the turbulence generator generates turbulence to reduce the drag of the ship while sailing.
 2. The structure for reducing the drag of a ship and its application according to claim 1, wherein the structure comprises a plurality of turbulence generators arranged adjacent to each other with a gap between them.
 3. The structure for reducing the drag of a ship and its application according to claim 1, wherein the structure comprises a plurality of turbulence generators arranged adjacent to each other as a stripe without a gap.
 4. The structure for reducing the drag of a ship and its application according to claim 1, wherein the turbulence generator has an impact surface, said impact surface has an intersection angle of not more than 60 degrees with the keel line of the ship.
 5. The structure for reducing the drag of a ship and its application according to claim 4, wherein said impact surface of the turbulence generator is parallel to the keel line of the ship.
 6. The structure for reducing the drag of a ship and its application according to claim 1, wherein the configuration of the turbulence generator is a rectangle, a slanted-face rectangle, a polygon, a trapezoid, a triangular pyramid, a pyramid, a cone, a semi-circular cone or a semi cone.
 7. The structure for reducing the drag of a ship and its application according to claim 1, wherein the turbulence generator is adhered, embedded or welded to the surface of the hull, or integrally installed with the hull.
 8. The structure for reducing the drag of a ship and its application according to claim 1, wherein the turbulence generator is made of metal, plastic, wood, bamboo, glass, ceramic or composite materials. 